There are a variety of different types of golf ball constructions, the majority of which, however, fall into two general categories: solid and wound golf balls. Solid golf balls include one-piece, two-piece, and multi-layer golf balls. One-piece golf balls are inexpensive and easy to construct, but have poor playing characteristics and are, therefore, usually limited for use as range balls. Two-piece balls are generally constructed with a polybutadiene solid core and a cover and are typically the most popular with recreational golfers because they are very durable and provide good distance. These balls are also relatively inexpensive and easy to manufacture, but are regarded by top players as having limited playing characteristics. Multi-layer golf balls are comprised of a solid core and a cover, either of which may be formed of one or more layers. These balls are regarded as having an extended range of playing characteristics, but are more expensive and difficult to manufacture than are one- and two-piece golf balls.
Wound golf balls, which typically include a fluid-filled center surrounded by tensioned elastomeric material and a cover, generally provide higher spin and soft “feel” characteristics but are more difficult and expensive to manufacture than are one-piece, two-piece, and multi-layer golf balls. Manufacturers are, therefore, constantly striving to produce a solid ball that incorporates the beneficial characteristics of a wound construction.
A variety of golf balls have been designed by manufacturers to provide a wide range of playing characteristics, such as compression, velocity, “feel,” and spin. These characteristics can be adjusted and optimized for a variety of playing abilities. For example, manufacturers can adjust these properties by altering the materials (i.e., polymer compositions) and/or the physical construction of each or all of the various golf ball components (i.e., centers, cores, intermediate layers, and covers). Polymers commonly employed by manufacturers for the construction of golf balls include polybutadiene (cores), ionomers, such as SURLYN, commercially available from DuPont (covers and intermediate layers), and polyurethanes (covers and intermediate layers). Finding the right combination of core and layer materials and construction to produce a golf ball suited for a predetermined set of performance criteria, in particular, increased resilience and, therefore, velocity, without a loss in “feel” is a task that is challenging.
It is desirable, therefore, to construct a ball having increased resilience formed of a soft, thin, urethane cover layer combined with a harder, thin ionomer casing, according to the present invention. This construction, coupled with a high-Mooney-viscosity polybutadiene core, also described by the present invention, has been found to raise the velocity of a golf ball prepared in this manner without detrimentally affecting desirable ball characteristics, such as spin, “feel,” and resiliency.